# HG changeset patch
# User Bram Moolenaar <Bram@vim.org>
# Date 1651866302 -7200
# Node ID b44f15083faf479b732c437c8ed22cf0dba00519
# Parent  da9f84bdc1c8cd85050d10280880066791cad5f6
patch 8.2.4895: buffer overflow with invalid command with composing chars

Commit: https://github.com/vim/vim/commit/d88934406c5375d88f8f1b65331c9f0cab68cc6c
Author: Bram Moolenaar <Bram@vim.org>
Date:   Fri May 6 20:38:47 2022 +0100

    patch 8.2.4895: buffer overflow with invalid command with composing chars

    Problem:    Buffer overflow with invalid command with composing chars.
    Solution:   Check that the whole character fits in the buffer.

diff --git a/src/ex_docmd.c b/src/ex_docmd.c
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -3435,7 +3435,7 @@ append_command(char_u *cmd)
 
     STRCAT(IObuff, ": ");
     d = IObuff + STRLEN(IObuff);
-    while (*s != NUL && d - IObuff < IOSIZE - 7)
+    while (*s != NUL && d - IObuff + 5 < IOSIZE)
     {
 	if (enc_utf8 ? (s[0] == 0xc2 && s[1] == 0xa0) : *s == 0xa0)
 	{
@@ -3443,6 +3443,8 @@ append_command(char_u *cmd)
 	    STRCPY(d, "<a0>");
 	    d += 4;
 	}
+	else if (d - IObuff + (*mb_ptr2len)(s) + 1 >= IOSIZE)
+	    break;
 	else
 	    MB_COPY_CHAR(s, d);
     }
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -3353,6 +3353,17 @@ func Test_cmdline_complete_scriptnames()
   set wildmenu&
 endfunc
 
+" this was going over the end of IObuff
+func Test_report_error_with_composing()
+  let caught = 'no'
+  try
+    exe repeat('0', 987) .. "0\xdd\x80\xdd\x80\xdd\x80\xdd\x80"
+  catch /E492:/
+    let caught = 'yes'
+  endtry
+  call assert_equal('yes', caught)
+endfunc
+
 " Test for expanding 2-letter and 3-letter :substitute command arguments.
 " These commands don't accept an argument.
 func Test_cmdline_complete_substitute_short()
diff --git a/src/version.c b/src/version.c
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4895,
+/**/
     4894,
 /**/
     4893,